Evolution is a long process to get from one species to a completely separate one. The initial species that the new species evolves from doesn't just morph into it's evolved ascendant. The ascended species is and offshoot of the main species that ended up living in a different environment from it's origns. So if you wanted your chicken to turn into a shark, not only would it take the chicken to have to live and survive in a shark inhabitable environment, but it would also take millions of years of extremely slow mutations from birth after birth after birth until eventually, the chicken's dna, due to survival of the fittest and those small mutated birthed chickens having features that best suit the animal for surviving in that environment, eventually growing slowly over time, full functional gills and dorsal fin. It might not look exactly like a modern shark, but it would probably be a something like a chicken shark.... shark with a sharp beak/mouth like an octopus....
Evolution does not work how you are trying to make it sound. A monkey is not going to give birth to a full blown human.... IF monkeys were ever to evolve into a humanoid sentient being... for one they would probably end up looking like the apes on the movie planet of the apes.... especially way before they ended up looking like us... if the environment dictated the need for them to appear like us at all....